According to U.S. Pat. No. 4,079,918 an arrangement is provided for closing the tap hole of a metallurgical vessel in which a closure body that is insertable into the tap hole so as to leave free an annular gap relative to the tap hole wall, contains a compressed-gas conduit. The closure body preferably comprises an outer jacket that tapers towards the mouth of the compressed-gas conduit.
Such an arrangement serves for enabling a separation of metal and slag during tapping, wherein the known arrangement is particularly easy to handle and can be applied repeatedly, i.e. even when the lining of the tap hole has already been subject to wear. With this known arrangement, air of the environment streams through the annular gap into the tap hole according to the injector principle when the closure body is in the closing position. As a result the size of the annular gap is of decisive importance with respect to the sealing effect. In case of wear of the lining of the tap hole, the diameter of the tap hole will increase, so that towards the end of a converter campaign more air of the environment will be sucked in. This causes the sealing effect of the closure arrangement to be lowered or to be maintained only by blowing more compressed air into the tap hole. It is therefore necessary to service and repair the tap hole within certain spans of time, the diameter of the tap hole having to be restored to about its original size by applying refractory mass thereto. This maintenance work can be carried out only between two heats. The time consumption connected therewith results in an extension of the average heat time and thus a reduction in the production.